Black interference patterns on random surfaces
(problem was present in 4.11 also, at least. I would have thought this would have come up before but I can't find it anyway, so apologies if I repeat a question.)
I have a problem with black interference patterns appearing in a material, as per the following photo:
The pattern changes as you move the camera position.
The material is a bog-standard, nothing fancy one, based on the starter materials:
This also happens with other materials - some even simpler.
The material in question is applied to a large (but not very complex) mesh representing a small building:
When I click on the building in the editor (so that the orange outline appears around it), the interference patterns disappear, until I click onto something else.
The pattern only appears on some of the walls.
I've checked for duplicate polygons (which can cause that kind of jazzing) but there's only one poly in the affected areas, and only one copy of the mesh placed in the level. I've rebuilt the whole level with 'high' quality lighting, restarted the editor, and so on. The artifacts also appear when testing the level in a new process. I started creating the level (and materials) in an older version of the 4.xx engine, so possibly there are some compatibility issues. I also have collision hulls (generic convex hulls, though all cuboids, I think) imported with the mesh (from Lightwave - yeah, I know) using the UCX_ prefix in the layer names. Those collision hulls overlay the visible polygons (though that shouldn't in theory cause a problem?).
This is probably something very stupid and obvious, but does anyone have any pointers?
Thanks in advance.
asked Oct 12 '16 at 10:29 AM in Rendering
Ok, I think I fixed it. The dodgy wall was very, very, very slightly non-planar, and that apparently causes the engine to bork (even though the wall is decomposed into triangles, which can't be non-planar...).
Thanks for your help - and yes, I suck at modelling...
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